What is true about the stomachs of some fish species?

Certain fish species exhibit unique adaptations in their digestive systems, which can include the absence of a true stomach. A true stomach is defined as a specialized organ where enzymatic digestion occurs. In some fish, notably certain species of bony fish, the design of their digestive tract may lack this distinct stomach structure, relying instead on other mechanisms for digestion.

For example, filter-feeding fish such as some species of carp or certain types of soil-dwelling fish might not have a well-defined stomach cavity, using their intestines for digestion instead. This adaptation can be advantageous in their specific ecological niches.

The presence of variations in stomach structures also emphasizes the diversity of evolutionary adaptations in fish. While many fish do have a true stomach that balances muscular contraction with digestive function, the statement about some fish not having a true stomach accurately reflects the broad spectrum of anatomical adaptations found in fish.